The elderly man from the town of Sittensen was walking to a dog kennel in his garden around 10 pm on Monday when he was approached by the group, who forced him back inside his home, police spokesman Detlev Kaldinski said in a statement.
There they stole his wallet and moved on to search the rest of the house.
But when they set off an alarm trying to open a safe, the pensioner decided to defend himself.
“The retiree, who as a hunter is also a gun owner, was able to get a pistol, shooting one offender dead,” the statement said.
Police await confirmation, but believe he was a 16-year-old German-Albanian boy with a long record of criminal activity. An autopsy is pending.
The other four burglars fled.
The suspects are reportedly between 20 and 30-years-old and speak broken German. They were of average stature and wearing dark clothing.
Overnight authorities launched a widespread search for the suspects, sending some 30 officers out with scent dogs, infrared cameras and a helicopter.
Witnesses in the area have been asked to report any suspicious activity in the area, particularly any speeding vehicles headed towards Appel.